diff --git a/Data/Heap/Internal.hs b/Data/Heap/Internal.hs
--- a/Data/Heap/Internal.hs
+++ b/Data/Heap/Internal.hs
@@ -30,6 +30,7 @@
 import Control.Exception
 import Data.Foldable ( Foldable(foldl, foldr, foldMap), foldl' )
 import Data.List ( groupBy, sortBy )
+import Data.Semigroup
 import Data.Monoid
 import Data.Ord
 import Data.Typeable
@@ -65,6 +66,9 @@
 
 instance (Ord prio, Ord val) => Ord (HeapT prio val) where
     compare = comparing toPairAscList
+
+instance (Ord prio) => Semigroup (HeapT prio val) where
+    (<>) = union
 
 instance (Ord prio) => Monoid (HeapT prio val) where
     mempty  = empty
diff --git a/Test.hs b/Test.hs
--- a/Test.hs
+++ b/Test.hs
@@ -9,7 +9,7 @@
 main :: IO ()
 main = do
     putStrLn "Ensuring assertions are not ignored:"
-    result <- quickCheckWithResult (Args Nothing 1 1 1 True) $ expectFailure (assert False True)
+    result <- quickCheckWithResult (Args Nothing 1 1 1 True maxBound) $ expectFailure (assert False True)
     putStrLn ""
     case result of
         (Success _ _ _) -> do
diff --git a/changes b/changes
--- a/changes
+++ b/changes
@@ -1,4 +1,9 @@
-Latest version: 1.0.2
+Latest version: 1.0.4
+
+1.0.3 --> 1.0.4
+===============
+- declared needed Semigroup instance for HeapT's Monoid instance
+- adapted to QuickCheck 2.10
 
 1.0.1 --> 1.0.2
 ===============
diff --git a/heap.cabal b/heap.cabal
--- a/heap.cabal
+++ b/heap.cabal
@@ -1,5 +1,5 @@
 Name:                heap
-Version:             1.0.3
+Version:             1.0.4
 
 Category:            Data Structures
 Synopsis:            Heaps in Haskell
@@ -23,7 +23,7 @@
   Location: git://github.com/3of8/heap.git
 
 Library
-  Build-Depends:     base >= 3 && < 5
+  Build-Depends:     base >= 4.6 && < 5
   Exposed-Modules:
       Data.Heap
   Other-Modules:
@@ -52,7 +52,7 @@
     , Test.Heap.Common
     , Test.Heap.Internal
     , Test.Heap.Item
-  Build-Depends:     base >= 3 && < 5, QuickCheck >= 2.3 && < 3
+  Build-Depends:     base >= 4.6 && < 5, QuickCheck >= 2.10 && < 3
   CPP-Options:       -D__TEST__
   GHC-Options:       -Wall -fwarn-tabs -fno-ignore-asserts
   Default-Language:  Haskell2010